WO2019239815A1

WO2019239815A1 - Secret-key sharing system and secret-key sharing method

Info

Publication number: WO2019239815A1
Application number: PCT/JP2019/020022
Authority: WO
Inventors: 藤原　幹生; 佐々木　雅英; 武岡　正裕; 寛之遠藤
Original assignee: 国立研究開発法人情報通信研究機構
Priority date: 2018-06-15
Filing date: 2019-05-21
Publication date: 2019-12-19
Also published as: JP2019220762A; JP7120607B2

Abstract

[Problem] To provide a secret-key sharing system and a secret-key sharing system method that perform sharing of a secret key between a transmitter device and a formal receiver device by using optical space communication. [Solution] A transmitter device 11 generates a secret key of optical space communication and RF band communication and distributes the secret key to a formal receiver device 14 by the optical space communication and the RF band communication. The transmitter device 11 receives information on the secret key selected by the formal receiver device 14, generates an optical-space communication secret-key and an RF-band communication secret-key, generates a final secret key to be shared with the formal receiver device 14 on the basis of a shared random number sequence included in the generated optical-space communication secret-key and the RF-band communication secret-key, and shares the final secret key with the formal receiver device 14.

Description

Secret key sharing system and secret key sharing method

The present invention relates to a secret key sharing system and a secret key sharing method for sharing a secret key between a sender device and an authorized receiver device using optical space communication.

Developed in recent years not only in Japan but also in overseas research institutes for the realization of quantum computers in recent years, and the realization of qubit computers corresponding to large-capacity qubits is expected in the future. Although this large-capacity qubit computer can be realized in principle, it has been said that it takes enormous processing time. Current encryption methods require security against the discrete logarithm problem and the mathematical difficulties of prime factorization, but when this qubit computer is realized, such mathematical difficulties are not. Even if the code is provided, it may be deciphered. Therefore, threats such as eavesdropping on confidential information by a third party (wiretapping) occur. Furthermore, since the performance of computers is improving year by year, there is a risk that the safety of security technologies such as encryption technologies may be reduced due to advanced computational capabilities and decryption algorithms.

Quantum key distribution (QKD) has been proposed as a technique for securely sharing an encryption key as an encryption method that counters the threats described above and wiretapping by a third party. This QKD is a quantum communication method for decoding encoded communication resources using a quantum state using a quantum communication channel. The transmitter encodes information input by an encoder that performs QKD using a quantum effect, and transmits the encoded information to a communication path as a communication resource. The receiving party can obtain the target information by receiving the communication resource transmitted to the communication path and decrypting the communication resource with the decombiner (see, for example, Patent Document 1). With QKD, it is possible to share a random number that is safe in terms of information theory between two distant parties.

However, since the current fiber-based QKD imposes strong restrictions on the distance and speed at which keys can be provided, the key generation rate is about several k to 1 Mbps when the transmission distance is about 50 to 100 km. For this reason, QKD experiments using satellites have been conducted with the aim of extending the key distribution distance of QKD. For example, in other countries (China), there have been reports of successful key generation between satellites and ground stations that are more than 1200 km away, but in QKD using satellites, the time for which the ground stations can track hygiene is limited . In addition, since it is difficult to increase the speed of a QKD device mounted on a satellite, the key generation rate is at most about 1 kbps. The index value of the security of the key, which is a safety parameter, is also set to a numerical value lower than that used in the ground-based fiber-based QKD device. Also, the information theory based on safety is not the latest, and there is room for improvement in key security.

鍵 Key security is information-theoretically secure, and there is a craving for technology that allows safe keys to be shared throughout Japan or between continents. In recent years, research on physical layer cryptography that enables secure information generation for information processing even when the ability of an eavesdropper assumed in QKD can be limited has been actively conducted.

In these studies, for example, in the wire tap model, the reception / retransmission attack assumed in QKD is not assumed. Therefore, if it is possible to know what signal has passed to the eavesdropper using the physical layer encryption, a secure key can be generated using the public communication path together. In addition, if an inevitable noise source can be set for an eavesdropper, the communication performance superior to QKD is achieved by a secret key sharing protocol that enables secure key generation due to the difference in signal-to-noise ratio between regular transceiver devices. May be possible.

For example, a virtual eavesdropper with a strong receiving capability is installed near a legitimate receiver device in a line-of-sight communication channel for optical communication, and it is regarded as the maximum amount of information leaked to a true eavesdropper and secure key generation is performed Has been proposed and verified (see Non-Patent Document 1, Non-Patent Document 2, for example). In these proposals and demonstrations, taking advantage of the characteristics of the optical communication line-of-sight communication channel, the communication channel is monitored with a telescope, a camera, etc., and the security of the key is discussed under the assumption that there are no eavesdroppers on the optical communication line. are doing. However, the monitoring capability of the line-of-sight communication channel with the existing camera is only about 10 cm in size because the image is fluctuated by the atmosphere, and even if space debris monitoring technology is introduced, it is about 10 cm. This is a level at which an object (such as a small photodetector) can be identified (see Non-Patent Document 3, for example).

JP 2004-104345 A

By the way, in the QKD technology including Patent Document 1 and Non-Patent Documents 1 to 3 described above, there is an assumption that an eavesdropper on the line-of-sight communication channel can perform all actions such as using a quantum memory and a quantum computer. For this reason, strong restrictions must be imposed on the key generation speed and service distance. Moreover, even if an object having a size of 10 cm or less (such as a small detector) is installed by an eavesdropper in the middle of a line-of-sight communication channel, it cannot be identified, so it is difficult to eliminate danger or risk from eavesdropping. .

On the other hand, in the RF band (RF: Radio Frequency), considering the implementation of physical layer encryption using an RF band lower than 750 MHz, the antenna size must be at least equivalent to a wavelength of 10 cm. Therefore, it is difficult to reduce the size of the detection system as described above. If a detection system is installed on the line-of-sight channel by an eavesdropper, an antenna having a size of at least 10 cm is required, so that an eavesdropper can easily find an eavesdropper. However, in RF band communication using an antenna, band limitation and directivity are inferior to those in the case of communication using light.

Accordingly, the present invention has been devised in view of the above-described problems, and the object of the present invention is to provide a secret key sharing system and a secret key sharing system that can perform key sharing more safely in a line-of-sight communication channel. It is to provide a method.

The secret key sharing system according to the first invention is a secret key sharing system for sharing a secret key between a sender device and a legitimate receiver device arranged in a line-of-sight communication channel, A key distribution unit that generates a secret key for optical space communication and RF band communication by modulating a random number sequence to be registered, and distributes the generated secret key to an authorized receiver device via optical space communication and RF band communication And a communication secret that receives information on the secret key selected by the authorized receiver device based on the distribution of the key distribution unit and generates an optical space communication secret key and an RF band communication secret key based on the received information. Based on a common random number sequence included in the optical space communication secret key and the RF band communication secret key generated by the key generation unit and the communication secret key generation unit, a final secret key to be shared with the authorized receiver device is determined. Final secret key generated And the authorized receiver device receives a secret key distributed via the optical space communication and the RF band communication by the key distribution unit, and selects and transmits the secret key to the sender device. It is characterized by having.

In the secret key sharing system according to the second invention, in the first invention, the final secret key generation unit matches the final secret key with the optical space communication secret key and the RF band communication secret key formed by a random number sequence of the same length. It is characterized by producing | generating.

A secret key sharing system according to a third aspect of the present invention is a secret key sharing system for sharing a secret key between a sender device and a legitimate receiver device arranged in a line-of-sight communication channel. And generating a plurality of secret keys for optical space communication by superimposing the divided random number sequences, and setting a proper receiver device at the center of the optical space communication beam in advance. A key distribution unit that distributes a plurality of secret keys by beam wandering so as to include the center of the beam, and a plurality of secret keys selected by the authorized receiver device based on distribution by the key distribution unit Then, based on a common random number sequence included in the optical space communication secret key generated by the communication secret key generation unit and the communication secret key generation unit that generates the optical space communication secret key, the sender device and the regular reception key A final secret key generation unit that generates a final secret key to be shared by the receiver device, and the authorized receiver device receives the secret key distributed via the optical space communication by the key distribution unit and It has a transmission part which sorts and transmits to a sender device.

A secret key sharing system according to a fourth invention is characterized in that, in the third invention, the beam wandering range is set and distributed based on the assumed position of the leaked information estimation receiver and the position of the eavesdropper. And

A secret key sharing method according to a fifth aspect of the present invention is a secret key sharing method for sharing a secret key between a sender device and a legitimate receiver device arranged in a line-of-sight communication channel. A key distribution step of generating a secret key for optical space communication and RF band communication by modulating, respectively, and distributing the generated secret key from a sender device to an authorized receiver device via optical space communication and RF band communication; A secret key distributed via optical space communication and RF band communication in the key distribution process is received at the authorized receiver device and is selected and transmitted to the sender device, and is selected by the authorized receiver device. Information on the received secret key is received at the sender device, and generated in the communication secret key generating step and the communication secret key generating step for generating the optical space communication secret key and the RF band communication secret key based on the received contents. Final secret key generation step for generating a final secret key to be shared between the sender device and the regular receiver device based on a common random number sequence included in the optical space communication secret key and the RF band communication secret key It is characterized by having.

A secret key sharing method according to a sixth invention is a secret key sharing method for sharing a secret key between a sender device and a legitimate receiver device arranged in a line-of-sight communication channel. And generating a plurality of secret keys for optical space communication by superimposing the divided random number sequences, and setting a proper receiver device at the center of the optical space communication beam in advance. A key distribution process for distributing each of a plurality of secret keys by beam wandering so as to include the center of the beam, and a secret key distributed via optical space communication in the key distribution process is received by the regular receiver device. And transmitting the selected secret key to the sender device and receiving the plurality of secret keys selected by the authorized receiver device at the sender device to generate an optical space communication secret key. And generating a final secret key to be shared between the sender device and the regular receiver device based on a common random number sequence included in the optical space communication secret key generated in the communication secret key generation step. And a final secret key generation step.

According to the first to sixth inventions, optical space communication and RF band communication are used for quantum cryptography communication between the sender device and the authorized receiver device. For this reason, a secret key can be shared even in RF communication with a frequency lower than 750 MHz, which cannot be detected by an antenna having a length of 10 cm or less in RF band communication, but cannot be detected by an antenna of 10 cm or less in optical band communication. As a result, the result of coding another key with one key is used as the final key common to the sender device and the authorized receiver device, so that information to an eavesdropper with a wide beam divergence angle of RF band communication can be obtained. It is possible to safely implement a common secret key that makes it possible to eliminate threats due to leakage and the presence of an eavesdropper on a communication path in optical space communication.

In particular, according to the second invention, a final secret key is generated by matching an optical space communication secret key and a radio frequency band communication secret key formed of a random number sequence of the same length. For this reason, the reception capability of an eavesdropper can be limited as compared with channel coding and secret key sharing for optical space communication only or RF band communication only. As a result, even if an eavesdropper is present in the communication path, safe key sharing is possible between the sender device and the authorized receiver device.

In particular, according to the third invention, by changing the central axis of the light beam in the vicinity of the authorized receiver device and transmitting, a plurality of light beams from the sender device are provided, and the range image of the light beam is expanded as a whole. For this reason, it is assumed that the maximum amount of information leaked to the eavesdropper is given, and secure key generation and sharing are possible between the sender device and the authorized receiver device. When the spread range is large, it is divided into a plurality of ranges, so that the light beam spread angle can be effectively narrowed, and the secret key can be shared safely.

In particular, according to the fourth invention, the message is divided and transmitted according to the number of times of beam wandering. For this reason, even if only one eavesdropper eavesdrops, the whole picture is not known. Thereby, even if there is an eavesdropper in the communication path, key sharing can be realized safely and at high speed. Furthermore, information leakage due to the light beam divergence angle due to optical space communication can also be suppressed. Thereby, it becomes a very powerful method for realizing the physical layer encryption in the sender apparatus and the authorized receiver apparatus, and the secret key can be shared safely.

In particular, according to the fifth invention, optical space communication and RF band communication are used for quantum cryptography communication between the sender device and the authorized receiver device. For this reason, a secret key can be shared even in RF communication with a frequency lower than 750 MHz, which cannot be detected by an antenna having a length of 10 cm or less in RF band communication, but cannot be detected by an antenna of 10 cm or less in optical band communication. As a result, by coding the result of coding one key with another key as the final key, information leakage to an eavesdropper and communication path in optical space communication associated with the wide light beam divergence angle of RF band communication It becomes possible to eliminate the threat caused by the presence of an eavesdropper, and to share a secret key safely.

Particularly, according to the sixth invention, by changing the central axis of the light beam in the vicinity of the authorized receiver device and transmitting, a plurality of light beams from the transmitter device are provided, and the range image of the light beam is expanded as a whole. For this reason, it is assumed that the maximum amount of information leaked to the eavesdropper is given, and secure key generation becomes possible. When the spread range is large, the light beam spread angle can be effectively narrowed because it is divided into a plurality of ranges, and the secret key can be safely shared between the sender device and the authorized receiver device.

FIG. 1 is a schematic diagram showing an example of a secret key sharing system to which the present invention is applied. FIG. 2 is a block diagram showing an example of the configuration of the satellite 1 of the secret key sharing system to which the present invention is applied. FIG. 3 is a block diagram illustrating an example of a secret key sharing system according to the first embodiment. FIG. 4 is a schematic diagram showing an example of secret key sharing operation in the first embodiment. FIG. 5 is a schematic diagram illustrating an example of a secret key sharing system according to the second embodiment. FIG. 6 is a schematic diagram illustrating an example of secret key sharing operation according to the second embodiment. FIG. 7 is a schematic diagram illustrating an example of secret key sharing operation in the second embodiment.

Hereinafter, an example of a secret key sharing system according to an embodiment of the present invention will be described with reference to the drawings.

First Embodiment FIG. 1 is a schematic diagram showing an example of a secret key sharing system 10 in this embodiment.

In the secret key sharing system 10 of the present embodiment, as shown in FIG. 1, the secret key sharing system 10 is based on quantum key distribution using the satellite 1, the two ground stations 2 and the antenna 3, and can share secret keys on a global scale. Become. The satellite 1 is a sender device 11, and the ground station 2 and the antenna 3 are regular receiver devices 14. The regular receiver device 14 is a device on the other side that the sender device 11 truly wants to share a secret key.

The legitimate receiver device 14 performs processing such as bit error and error correction according to the reception status, and sorts the secret key distributed from the sender device 11. The ground station 2 in the regular receiver apparatus 14 performs, for example, optical space communication from the satellite 1 with a telescope. Further, the antenna 3 in the regular receiver device 14 performs RF band communication with the satellite 1 using radio waves in the RF band.

FIG. 2 is a block diagram showing an example of the configuration of the satellite 1 of the secret key sharing system to which the present invention is applied.

The satellite 1 includes a key distribution unit 4, a communication secret key generation unit 5, and a final secret key generation unit 6 as shown in FIG. The key distribution unit 4 includes an optical space communication key distribution unit 41 and an RF band communication key distribution unit 42. The key distribution unit 4 modulates the random number sequence to generate each secret key in the optical space communication key distribution unit 41 and the RF band communication key distribution unit 42, and uses the generated secret key for optical space communication and RF It is distributed to the ground station 2 and the antenna 3 via band communication.

The optical space communication key distribution unit 41 generates a random number sequence modulated by a physical random number generator mounted on the satellite 1. This random number sequence may be registered in advance. The optical space communication key distribution unit 41 distributes the generated random number sequence to the ground station 2 by optical space communication using the quantum effect. This optical space communication may be transmitted by, for example, a light beam system provided in the satellite 1. In this case, the intensity of the light beam reaching the ground due to the intensity of the light beam, the diaphragm, or the like may be determined. The beam light may be distributed while being set so that the position of the ground station 2 becomes the center of the beam light, for example.

The RF band communication key distribution unit 42 distributes the random number sequence modulated by the physical random number generator to the antenna 3 by RF band communication. The communication secret key generation unit 5 receives the secret key selected by the authorized recipient device 14 based on the distribution of the key distribution unit 4, and performs secret key matching.

The communication secret key generation unit 5 receives information on each secret key selected by the authorized receiver device 14. The communication secret key generation unit 5 matches the results selected based on the information about the secret key. The communication secret key generation unit 5 generates the selected optical space communication secret key and RF band communication secret key.

The final secret key generation unit 6 should be shared with the authorized receiver device 14 based on the common random number sequence included in the optical space communication secret key and the RF band communication secret key generated by the communication secret key generation unit 5 Generate the final secret key. For example, the final secret key generation unit 6 may be included in the authorized recipient device 14.

FIG. 3 is a diagram showing an overall configuration when an eavesdropper device 15 enters in a secret key sharing system to which the present invention is applied. FIG. 3 shows a case where there are a plurality of ground stations 2 distributed from the transmitter apparatus 11 (satellite 1) corresponding to the satellite 1 described above, one of which is a regular receiver apparatus 14 and the other is an eavesdropper apparatus 15. It is.

The regular receiver device 14 (the ground station 2 and the antenna 3) performs optical space communication with the transmitter device 11 (satellite 1) via the main communication path 12. The eavesdropper device 15 has a configuration corresponding to at least the ground station 2 and may further have a configuration corresponding to the antenna 3. The eavesdropper device 15 is a device that does not want the sender device 11 to share the secret key, and the eavesdropper device 15 performs optical space communication from the sender device 11 via the eavesdropper communication path 13 for the purpose of eavesdropping. And attempts to intercept RF band communications.

Next, the operation of the secret key sharing system 10 to which the present invention is applied will be described.

Satellite 1 modulates an intrinsic random number generated by an on-board physical random number generator (not shown) into a quantum state of light and distributes it to ground station 2 by optical space communication. Similarly, the satellite 1 modulates a true random number and transmits it to the antenna 3 by RF band communication. It should be noted that the physical random number generator is held in common with the regular receiver device 14 before the satellite 1 is launched.

The ground station 2 and the antenna 3 perform correction processing for deterioration of information distributed by the optical space communication and the RF band communication distributed from the satellite 1 based on the intrinsic random numbers already held. This correction processing is, for example, bit error or error correction. As a result, the satellite 1 can generate an optical space communication secret key and an RF band communication secret key based on information (correction information, etc.) related to the secret key transmitted from the authorized receiver device 14, and holds a common secret key. be able to.

Satellite 1 receives sorting result information from ground station 2 and antenna 3 through optical space communication and RF band communication. The communication secret key generation unit 5 in the satellite 1 matches the random number sequence distributed by the optical space communication and the RF band communication based on the selection result information. Based on the matching result, an optical space communication secret key and an RF band communication secret key are generated.

The final secret key generation unit 6 prepares the same number of bits from the optical space communication secret key and the RF band communication secret key generated at different wavelengths according to the above-described processing. As shown in FIG. 4, the final secret key generation unit 6 calculates, for example, an exclusive OR from the prepared number of bits for the optical space communication secret key and the RF band communication secret key, and the calculated result is used as the final secret key. To do.

The final secret key is calculated by, for example, exclusive OR for each bit in both the optical space communication secret key (Key 1) and the RF band communication secret key (Key 2). As a result, a common random number is generated as the final secret key, and this common random number is shared between the sender device 11 and the authorized receiver device 14.

As described above, according to the first embodiment, the final secret key is generated based on the selection result of the separate communication using the optical space communication and the RF band communication between the sender device 11 and the regular receiver device 14. To do. For this reason, even if either optical space communication or RF band communication is intercepted via the eavesdropper device 15, the final secret key cannot be reproduced from the eavesdropper device 15. For this reason, the authorized recipient device 14 can share the final secret key more safely without being intercepted by the eavesdropper device 15.

Second Embodiment Hereinafter, a second embodiment of the secret key sharing system 10 to which the present invention is applied will be described. In the second embodiment, the same components and members as those in the first embodiment described above are denoted by the same reference numerals, and the following description is omitted.

In the second embodiment, as shown in FIG. 5, only the satellite 1 is used as the transmitter device 11 and only the ground station 2 is used as the regular receiver device 14. Note that a configuration for generating a final key is preinstalled in the authorized recipient device 14.

The satellite 1 as the sender device 11 modulates a true random number generated by an on-board physical random number generator (not shown) into a quantum state of light, and a regular receiver device as the ground station 2 by optical space communication. 14 is delivered. The authorized receiver device 14 generates a final secret key to be shared with the sender device 11 based on the secret key distributed through the optical space communication.

Hereinafter, the optical space communication method according to the second embodiment will be described in detail.

The sender apparatus 11 presets the center of the light beam of the optical space communication with respect to the regular receiver apparatus 14. FIG. 6 shows a setting example of this light beam. At the time of setting the light beam, the center of the light beam of the optical space communication, the position of the regular receiver device 14 and the position of the eavesdropper device 15 are considered. Incidentally, the eavesdropper device 15 may be set to be a pseudo, so-called fictitious device.

In the following example, the detection capability of the eavesdropper device 15 is equivalent to that of the regular receiver device 14. Further, the eavesdropper device 15 can receive light with the same energy density as that of the eavesdropper device 15 with respect to one light beam from the transmitter device 11, and other light beams are separated by 1σ or more. Assume.

Under this assumption, the beam wandering range is set so as to include the center of the optical beam of optical space communication. The beam wandering light beams 30 to 32 in FIG. 6 are examples in which the center of the light beam for optical space communication is set to the authorized receiver device 14 and is set so as to include the center. The mutual light beams 30 to 32 are set so as not to be completely overlapped, and their centers are set so as to be shifted from the regular receiver apparatus 14.

In the second embodiment, the sender device 11 divides the random number sequence that is actually registered into a plurality of pieces. A plurality of secret keys are generated by superimposing the divided random number sequences. The key distribution unit 4 in the sender apparatus 11 distributes the secret key based on the divided random number sequence to each legitimate receiver apparatus 14 by superimposing it on each light beam to be beam wandered.

For example, as shown in FIG. 7, when the random number sequence is divided into three, that is, a divided secret key A, a divided secret key B, and a divided secret key C, at least three light beams to be beam wandered are set, A secret key is superimposed on each light beam and distributed to the authorized recipient device 14. In the example of FIG. 7, the divided secret key A is superimposed on the light beam 30, the divided secret key B is superimposed on the light beam 31, and the divided secret key C is superimposed on the light beam 32 for distribution.

These divided secret key A, divided secret key B, and divided secret key C are the difference between the error rate of each light beam and the estimated value of the leaked information amount in the transmitter device 11 and the regular receiver device 14 in optical space communication. The key length of the secret key may be different. For this reason, the legitimate receiver apparatus 14 that has received the beam wandered light beam, for example, the key length of the smallest secret key among the received divided secret key A, divided secret key B, and divided secret key C. Is used as a reference, and the key length obtained with each secret key is used, and a process of discarding a longer key is performed.

Then, the authorized receiver device 14 extracts a common random number from each exclusive OR based on the divided secret key A, the divided secret key B, and the divided secret key C. Then, the extracted common random number is wandered through the optical space communication and used as the final secret key shared by the authorized recipient device 14.

As shown in FIG. 6, the maximum approach distance in the actual eavesdropper device 15 is estimated by detecting the amount of leaked information through a pseudo-set leaked information estimation required receiver with the legitimate receiver device 14 as the center. be able to. In generating the final secret key, it is necessary to accurately acquire all of the divided secret keys with high strength. That is, if even one of the divided secret keys is missing, the final secret key cannot be generated.

In order for the eavesdropper device 15 to actually receive all of the beam wandered light beams, it is necessary to approach the same position as the regular receiver device 14 or close to its immediate vicinity, but in practice it is quite realizable. difficult. For this reason, the reception of the light beam by the eavesdropper device 15 becomes incomplete, and it is practically difficult to obtain the final secret key.

Therefore, the legitimate receiver device 14 can more securely share the final secret key without being intercepted by the eavesdropper device 15.

Note that the key distribution unit 4 may narrow the beam diameter of the light beam that is actually distributed, and then perform beam wandering. As a result, it is possible to reduce the information leakage accompanying the spread of the beam with extremely high efficiency.

Further, the secret key sharing method for sharing the secret key between the sender device and the regular receiver device arranged in the line-of-sight channel in the present embodiment includes the key distribution step in the secret key sharing system 10 described above, By having a transmission step, a communication secret key generation step, and a final secret key generation step, secret key sharing is possible even in RF communication at a frequency lower than 750 MHz that cannot be easily received by an antenna of 10 cm or less in RF band communication. It becomes.

As a result, by coding the result of coding one key with another key as the final key, information leakage to an eavesdropper and communication path in optical space communication associated with the wide light beam divergence angle of RF band communication It becomes possible to eliminate the threat caused by the presence of an eavesdropper, and to share a secret key safely.

Although embodiments of the present invention have been described, each embodiment is presented as an example and is not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

1: Satellite 2: Ground station 3: Antenna 4: Key distribution unit 5: Communication secret key generation unit 6: Final secret key generation unit 10: Secret key sharing system 11: Sender device 12: Main communication channel 13: Eavesdropper communication Path 14: Authorized receiver device 15:

Eavesdropper device

30, 31, 32: Light beam 41: Optical space communication key distribution unit 42: RF band communication key distribution unit A to C: Divided secret key

Claims

A secret key sharing system for sharing a secret key between a sender device and a legitimate receiver device arranged in a line-of-sight channel,
The sender device is
A key distribution unit that transmits a random number sequence using optical space communication and RF band communication, generates a secret key, and distributes the generated secret key to the authorized recipient device via optical space communication and RF band communication; ,
A communication secret key that receives information on the secret key selected by the authorized receiver device based on the distribution of the key distribution unit and generates an optical space communication secret key and an RF band communication secret key based on the received content A generator,
Based on a common random number sequence included in the optical space communication secret key and the RF band communication secret key generated by the communication secret key generation unit, a final secret key to be shared with the authorized receiver device is generated. A secret key generation unit,
The regular recipient device is
Receiving a secret key distributed through optical space communication and RF band communication by the key distribution unit, and having the transmission unit select and transmit the secret key to the sender device;
A secret key sharing system.
The final secret key generation unit generates the final secret key by matching the optical space communication secret key formed by a random number sequence of the same length and the RF band communication secret key;
The secret key sharing system according to claim 1.
A secret key sharing system for sharing a secret key between a sender device and a legitimate receiver device arranged in a line-of-sight channel,
The sender device is
Dividing the random number sequence into a plurality of numbers, generating a plurality of secret keys for optical space communication in which the divided random number sequences are respectively superimposed, and setting the regular receiver device at the center of the optical space communication beam in advance A key distribution unit that distributes each of the plurality of secret keys by beam wandering so as to include the center of the beam;
The regular recipient device is
Having a final secret key generation unit that generates a final secret key to be shared with the sender device based on a secret key included in each light beam distributed through optical space communication by the key distribution unit. A secret key sharing system.
The key distribution unit sets and distributes the beam wandering range based on the assumed position of the leaked information estimation receiver and the position of the eavesdropper,
The secret key sharing system according to claim 3.
A secret key sharing method for sharing a secret key between a sender device and a legitimate receiver device arranged in a line-of-sight channel,
By modulating the random number sequence, a secret key for optical space communication and RF band communication is generated, and the generated secret key is distributed from the sender device to the authorized receiver device via optical space communication and RF band communication. Key distribution process;
A transmission step of receiving the secret key distributed through the optical space communication and the RF band communication by the key distribution step at the regular receiver device, and selecting and transmitting the secret key to the transmitter device;
A communication secret key generation step of receiving information on the secret key selected by the regular receiver device at the transmitter device and generating an optical space communication secret key and an RF band communication secret key based on the received content,
Based on the common random number sequence included in the optical space communication secret key and the RF band communication secret key generated in the communication secret key generation step, the final secret to be shared between the sender device and the authorized receiver device Having a final secret key generation step of generating a key;
A secret key sharing method characterized by the above.
A secret key sharing method for sharing a secret key between a sender device and a legitimate receiver device arranged in a line-of-sight channel,
In the transmitter apparatus, the random number sequence is divided into a plurality of pieces, and a plurality of secret keys for optical space communication are generated by superimposing the divided random number sequences, respectively, and the regular receiver apparatus is A key distribution step of distributing each of the plurality of secret keys by beam wandering so as to include the center of the beam while being set in advance,
A final secret key for generating a final secret key to be shared with the sender device based on a secret key included in each light beam distributed to the authorized receiver device via optical space communication in the key distribution step Having a generation step,
A secret key sharing method characterized by the above.